To elucidate the neuronal mechanisms involved in the initiation and visual guidance of eye movements and in the selective fixation of targets, the behavior of single neurons was studied in the flocculus of the monkey during fixation, and during saccadic and smooth pursuit eye movements. We discovered that the majority of Purkinje cells ceased firing before and during saccades, while showing considerably high level of tonic discharge during fixation. When the monkey tracked a target undergoing sinusoidal excursions, the discharge of Purkinje cells was modulated in phase with target and eye position. There were also cells whose activity reflected target and eye velocity or the acceleration. It is known that Purkinje cells exert inhibitory synaptic action upon their direct target neurons. The high level of tonic discharge in fixation and the complete cessation duing saccades would indicate that the flocculus sends tonic inhibitory impulses to eye movement neurons during fixation, the disruption of which may result in a disinhibitory action upon these neurons during saccades. During smooth pursuit eye movements the flocculus would provide the neurons with the information of position, velocity and acceleration.